One approach to targeting information is unicast addressing. Each message sent contains a particular numeric address. Devices that receive the message compare the address value with an address stored in the device and only deliver the message if the two match. Another form of targeting is multicast addressing where certain ranges or types of addresses are prearranged to represent groups of devices rather than individual devices. A receiving device delivers the message if the message address matches the receiving device's specific address or that of any of the multicast groups configured into the receiving device.
Another approach involves addressing by labels rather than by numeric addresses. For example, a sender inserts a label into the message describing the type of receiver desired, such as a printer. Each receiver stores a set of labels and delivers messages that match at least one of the labels.
The above forms of targeting are forms of “push” targeting in which the sender identifies the recipient(s) of the message based on the address or label inserted into the message. Another form of targeting is “pull” targeting in which the receiving device determines which sent messages to deliver. For example, a form of pull targeting consists of inserting a text string that describes or identifies the contents of the message in the transmitted message. This text string is called a “descriptor.” One form of descriptor is a stock ticker symbol, and this descriptor is inserted into any message containing news stories about the company identified by that symbol. Receiving devices store a set of descriptors and deliver messages whose descriptor match at least one of the stored descriptors.
In another form of pull targeting, the descriptor stored in a message is a structured set containing one or multiple elements that collectively describe or identify the contents of the message. Each element of the descriptor may be a string or a numeric value or other data type. Receiving devices store a set of logical formulas, each of which is evaluated against the elements of the descriptor in the message. If one or more of the formulas evaluate to true, the message is delivered.
It is an important object of the invention to provide improved targeting.